(1) Field of the Invention
The invention relates to the fabrication of integrated circuit devices, and more particularly to a new configuration of a multiple chamber vacuum processing system (MCVPS) for the purpose of improving the positional stability of the wafer mark shielding process,
(2) Description of the Prior Art
The prior art of semiconductor processing including plasma etching, CVD deposition, physical sputtering, etc. has progressed from single vacuum chamber batch-type systems performing a single processing operation upon a plurality of small diameter single part-numbered wafers made of semiconductor material which typically were manually or semi-automatically loaded into the process chamber for the purpose of high throughput.
Since that time, semiconductor circuit design requirements, manufacturing economics and necessary higher product yields have driven the industry to develop and utilize manufacturing equipment to operate on relatively fewer but much larger wafers possibly containing a multiple of part numbers with finer geometry and dimensions but requiring precise automatic material handling. Such yield enhancement and flexibility needs demanded a higher level of automated in-situ integrated processing.
Manufacturing subsystems which are capable of doing a multiple of processes upon larger wafers in-situ became available in the mid 1980s.
U.S. Pat. No. 4,951,601 (Maydan et al., 1990) discloses an integrated modular multiple chamber vacuum processing system (IMMCVPS) which is capable of integrating a variety of types of integrated circuit processes such as deposition, sputtering, etching and annealing. It includes a robotics R-.theta. transfer means to move a wafer to and from external and internal wafer cartridge loading elevators as well as to and from single axis robotics mechanisms within each of the multiply appended process chambers.
U.S. Pat. No. 5,505,779 (Mizuno et al., 1996) illustrates in a context figure another of the prior art integrated module multi-chamber processing systems. Generic to this illustration is an R-.theta. transfer means within a single vacuum transfer chamber with six process chambers attached.
U.S. Pat. No. 5,292,393 (Maydan et al., 1994) further discloses the details of the R-.theta. robotics transfer system and its operation together with those of selected individual chamber cooperating single axis transfer means. More importantly, it illustrates how a plurality of such transfer chambers, utilizing only one external wafer cartridge, can be concatenated to provide a more complex system to handle additional serial or parallel processing operations. Although precision of the R-.theta. transfer movements is controlled by the rotation of concentric drive shafts, there is no teaching about maintaining the precise location, alignment or orientation of the wafer as it is transferred between the multitude of process steps, especially when the process steps require using concatenated transfer chambers.